With the expansion of telecommunications, wireless technology, and various information systems, a greater number of operational frequencies are needed to meet expected demand. The Ka-band is a relatively newly released satellite transmission frequency, deployed to accommodate this growing demand. It is assigned to a frequency range from about 20 GHz to about 30 GHz, wherein the reception occurs at about 20 GHz and the transmission occurs at about 30 GHz.
Ku-band is a relatively standardized satellite transmission frequency and has been one of the standards used for some time. It operates in about the 12 GHz range. One disadvantage with the Ku-band frequencies is that it is becoming less and less available as demand continues to soar in the telecommunications arena, i.e. the available usable frequencies are diminishing. It should be appreciated though that future technology will not merely dispense with the “aging” frequency because many systems will still rely on the Ku-band long into the future.
It is anticipated in the near future that a number of Ka-band satellites will be launched. A primary purpose for the dissemination of these Ka-band satellites is to provide, for example, broadband data services to homes and small businesses as well as address the growing limitations on the Ku-band frequencies, as mentioned above. A number of service providers actively developing this broadband service offering, have defined a need for a low cost, efficient ground terminal that can be used for a Ka-band service and at the same time may receive standard Fixed Satellite Service (FSS) and Direct Broadcast Satellite (DBS) Services operating in the International Telecommunications Union (ITU) defined Ku-band spectrum. This dual Ka-band receiving/transmitting functions along with the Ku-band receiving function is more generally referred to as a tri-band configuration.
At this time a number of technical solutions are under development or are being proposed, and most approaches do not meet the aggressive cost targets because of the prohibitive nature in developing units that operate to receive and transmit Ka-band satellite signals and also receive Ku-band signals. In one example, a co-axial feed comprising a feed horn is used as the solution to the tri-band configuration and is described by the Raytheon Company's, U.S. Pat. No. 6,720,933. However, the configuration disclosed in Raytheon's patent requires very tight and precise tolerances. These tolerance requirements make the unit cost prohibitive in a mass marketing scheme, i.e. to be able to provide the units to the general public at a low cost.
Another example, described by the U.S. Pat. No. 6,512,485 and assigned to WildBlue Communications, Inc., describes a tri-band reflector that encompasses a dichroic subreflector. In essence, the dichroic subreflector allows certain frequencies to filter through while reflecting others. Such a configuration allows the lower Ku-band frequency to pass through while reflecting the higher frequency Ka-band signals. However, this invention is also subject to very tight and precise manufacturing tolerances. Therefore the Wild Blue embodiments are also somewhat cost prohibitive in nature on a mass marketing level.
In still another example, some manufacturers attempt to utilize certain characteristics of folded optics to assemble a combination Ka-band/Ku-band transmitter-receiver. In general folded optics incorporate dual reflecting dishes and may also take into account the benefit of dual focal points. This also technology suffers from the same limitations as the above mentioned art. That is, the technology requires significant precision and tight tolerances that are generally too expensive to incorporate into a mass produced product that is attempting to satisfy the needs of a general public.
Therefore, a need exists for a low cost ground terminal configured to transmit or receive Ka-band satellite signals to provide, for example, broadband data services to homes and businesses, and at the same time, be able to receive standard FSS and DBS Services operating in the ITU defined Ku-band spectrum.